654 GUM ACACIA TRAGACANTH 



5 per cent. ; or nuclein solution (Parke, Davis, and Co.), 

 containing 5 per cent, of nucleinic acid, may be given hypo- 

 dermically to horses, in doses of 3iJ ss -> with an equal 

 quantity of physiological salt solution. 



GUM ACACIA-TRAGACANTH 



ACACIJE GUMMI. A gummy exudation from the stem and 

 branches of Acacia Senegal, and of other species of 

 Acacia (B.P.). 



TBAGACANTHA. Tragacanth. A gummy exudation ob- 

 tained by incision from Astragalus gummifer, and some 

 other species of Astragalus (B.P.). Nat. Ord. Legu- 

 minosae. 



Gum is obtained from many plants, notably from various 

 species of Acacia. These are stunted, withered-looking 

 trees, occurring in tropical countries, most prolific when 

 old and stunted, and during dry, hot seasons. In June and 

 July, from natural cracks or artificial incisions in the bark, 

 a viscid juice exudes, and concretes into round masses or 

 tears varying in size from a pea to a walnut, brittle, usually 

 shining, colourless, yellow or brown, odourless, and of a 

 bland, sweet taste. Gum dissolves in water, forming an 

 adhesive, viscid fluid or mucilage. 



Gum acacia, or gum arabic is chiefly collected in Kor- 

 dofan, in Eastern Africa, and forwarded from Alexandria. 

 When imported, it is picked and sorted, usually into three 

 different qualities, distinguished by the size, colour, and 

 transparency of the tears. It is soluble in about its own 

 weight alike of hot and cold water, is insoluble in and 

 incompatible with alcohol, ether, and oils. Boiled with 

 dilute sulphuric acid, it is converted into gum sugar ; oxi- 

 dised by nitric acid, it is converted into mucic acid. It 

 consists of arabin, or arabic acid, which occurs in gum as 

 arabate of calcium, magnesium, and potassium. 



Gum Senegal is similar to gum arabic, but less brittle, 

 and requires four or five parts of water to dissolve it. The 

 East Indian gums are generally dark-coloured, more difficult 

 of solution, and less valuable. The gums of Australia and 



